Fabric feeding device for sewing machines

ABSTRACT

The invention relates to a fabric feeding device for sewing machines which must travel along a rectangular path in order to grip and advance a fabric past the sewing needle and then release the fabric and return to a starting position. A pneumatic drive cylinder is employed to drive a fabric clamp, said cylinder being rotatable about its own axis in order to effect the respective movements of the clamp towards and away from the fabric.

United States Patent [191 Bianchi Jan. 14, 1975 [54] FABRIC FEEDING DEVICE FOR SEWING 3,362,301 1/1968 Kohlitz 92/2 MACHINES 3,416,407 12/1968 Renner et a]. 92/2 X [75] Inventor: Nereo Bianchi, Pavia, Italy [73] Assignee: Necchi S.p.A., Pavia, Italy [22] Filed: Jan. 25, 1974 [21] Appl. No.: 436,782

Related [1.8. Application Data [63] Continuation of Ser. No. 142,938, May 13, 1971,

abandoned.

[30] Foreign Application Priority Data May 15, 1970 Italy 42907/70 [52] US. Cl 112/76, 92/2 [51] Int. Cl D05b 3/04 [58] Field of Search 112/76, 77, 70, 65; 92/2; 91/173 [5 6] References Cited UNITED STATES PATENTS 3,349,732 10/1967 Perrella et al 112/65 Primary Examiner-H. Hampton Hunter Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT The invention relates to a fabric feeding device for sewing machines which must travel along a rectangular path in order to grip and advance a fabric past the sewing needle and then release the fabric and return to a starting position. A pneumatic drive cylinder is employed to drive a fabric clamp, said cylinder being rotatable about its own axis in order to effect the respective movements of the clamp towards and away from the fabric.

4 Claims, 4 Drawing Figures PATENIEBJAN 1 mars SHEET 3 [IF 3 FABRIC FEEDING DEVICE FOR SEWING MACHINES This a continuation .of application Ser. No. 142,938, filed May 13, 1971 and now abandoned.

The present invention refers to a fluid operated fabric feeding device applied to sewing machines which effect groups of stitches, and particularly to button or button-hole sewing machines, which are adapted to execute successive sewing operations at a pre-arranged distance apart from each other.

Already known in the art are devices which are operated pneumatically and are suitable for automatic feed ing of the fabric past the sewing needle. Such known machines are provided with an arm which moves along a rectangular path which arm is driven by pneumatic motors. The translations of the arm along one pair of the parallel sides of the rectangle are used for moving the arm transversely relative to the fabric, while the translations along the other pair of parallel sides of the rectangle are used to feed the fabric, and to carry the arm back to its start position, ready to begin another feeding phase. Said types of known devices are remarkably complex, need excessive space and are costly.

An object of the present invention is to provide a new type of simple working device, not very bulky and having a rather low cost.

According to the present invention, the resolution of the technical problem is realized by means of a driving cylinder whose piston rod is rigidly connected to an arm, means being provided to cause said cylinder to oscillate rotatively together with its piston rod, the rod only reciprocating axially in alternating sequence to the cylinder oscillations so that said arm is caused to follow a rectangular path.

The features and advantages mentioned above and not restrictive of the invention will be apparent from the following description and from the attached drawings in which:

FIG. 1 is a plan view of the device according to the invention;

FIG. 2 is a cutaway view of the device of FIG. 1 taken along line 2-2;

FIG. 3 is acutaway view of the device of FIG. 1 taken along line 3--3 and FIG. 4 is a side elevational view of the fabric feeding device attached to a sewing machine.

Drive cylinder is rotatively supported within C- shaped support member 11 which in turn is fixed to the not shown bed of the machine by screws 12. Cylinder 10 defines a piston chamber 19 within which piston 18 reciprocates together with its rod 17 which extends outwardly of the cylinder through a bore 16 in fixed seal element 15. Seal rings 20 and 21 serve to prevent air leakage past the rod and past the seal element into chamber 19.

At the other end of piston rod 17, a screw 23 is locked by means of nut 22, which at the end of the stroke of said piston rod 17, acts against rod 24 of a three-way valve 25 which is fixed, to a mounting member 27, by means of a nut 26. Said member 27 is fastened to drive cylinder 10 by means of screws 28, as shown in FIG. I. Said member 27 has a central guide 29 along which a square block 30 slides and is connected toa tie member 32 by means of a pin screw 31, said tie member 32 being fastened to piston rod 17.

An arm 33 .(FIG. I), integral with said piston rod 17, comprises a part 34 fastened at one end to said piston rod 17, by means of a tie not shown in the drawings, and carries, pivoted at the other end a rod 35, a shaft 36 being fixed thereto by means of tie 9 and screw 14 and carrying at its free end a pad 37. A second pad 38 is connected directly to rod 35 at a suitable distance from the first pad. The distance between the two pads 37 and 38 can be changed within certain limits, by loosening screw 14 and causing shaft 36 to slide into hollow rod 35. Said pads 37 and 38 have the task of frictionally engaging the fabric and carrying and positioning an adjustable and pre-arranged amount of said fabric under the needle that will effect successive stitchings thereon.

At the other end, cylinder 10 is closed by a cylindrical body 39 having a circumferential groove 40, in which a rubber gasket 41 is placed and an axial hole44, the function of which will be described hereinafter.

Cylindrical body 39 is rigidly fastened along the inner portion of a second cylindrical body 42 which is externally threaded along a smaller diameter portion thereof. Said cylindricaly body 42 can be adjusted axially to assume different positions relative to chamber 19.

A ring nut 43 prevents said cylindrical body 42 from moving axially relative to any pre-arranged position, during operation of the device. In this way, the distance between successive button-holes will be kept uniform as will be described hereinafter.

Mounting member 27 has a fork 45 at its end which is fixed to cylinder 10. Said fork 45 cooperates with a square element 46 connected to piston member 49 by means of a screw pin 48. Said piston member 49 can slide within a cylindrical cavity 50 (FIG. 3) in the body 51 of C-shaped member 11. Said cavity 50 is closed at its ends by means of covers 52 and 52' fixed to body 51 by means of screws 53.

Said covers 52 and 52 comprise annular extensions 54 and 54 respectively which extend axially into the cylindrical cavity 50 thus delimiting by their ends 55 and 55' the stroke of piston member 49. Said piston member 49 comprises axially opposed cylindrical prolongations 56 slidable within extensions 54 and 54' said cylindrical prolongations 56 having smaller diameter than the central portion of 49 and being provided with a circumferential groove 57 in which a rubber gasket ring 58 is fitted. Covers 52 and 52' are provided with holes 59 and 59', respectively, suitable to put the respectivecylindrical cavities in communication with a compressed air source provided by the pneumatic system driving the device.

When piston 49 slides within cavity 50, it drags along the screw pin 48 and the square element 46 connected thereto, as described hereinabove.

The displacement of said square element 46 in fork 45 causes the rotation of mounting member 27 fixed thereto, and therefore the rotation of cylinder 10 fixed to said member 27, about the axis of the cylinder itself. During such rotation, a plate 60 fixed to mounting member 27 by means of screw 61 (FIG. 1), acts against a ball member 62 of pilot member 63 of a four way valve 64 whose function will be described hereinafter.

Holes 65 are provided in C-shaped member II to allow lubrication of the parts of cylinder 10 which are rotatably supported in mounting member 111.

The fabric feeding movements are imparted to arm 33 by the-oscillatory rotations and the axial displacements of piston rod 17 which occur in alternate succession, as described hereinafter.

At the beginning of a feeding cycle piston member 49 is in the position shown in FIG. 3. Then compressed air supplied by the suitable system through hole 59 enters such movement causes therotation of mounting member 27 androtation of cylinder and'piston rod 17 with the consequent lowering of pads 37 and 38 onto the fabric piece to be fed. At this point, compressed air passes through axial hole 44 and into chamber 19 of cylinder 10 and displaces piston 18 toward seal element 15. Fabric is thereby dragged by the two pads 37 and 38 which move integrally with piston rod 17 of piston 18. At the end of this stroke of piston 18, member 23 at the end of piston rod 17 switches the valve 25 which causes air to flow into cylindrical cavity 50 of body 51 through hole 59.

Piston '49 therefore displaces towards hole 59' and such displacement causes an axial rotation of piston rod 17 and of cylinder 10 opposite to that described previously, and the consequent lifting of pads 37 and 38 away from the fabric.

' After lifting of the pads" 37 and 38, compressed air passes through hole 66 (FIG. 2) in cylinder wall 10, a circumferential groove 67 in seal element 15, and holes 68 parallel to the axis of said element 15, and enters chamber 19.thereby displacing piston 18 towards hole 44 causing piston 18 and piston rod 17 to return to the position of FIG. 2 corresponding to the beginning of a new phase of fabric feeding.

In order to obtain a variation in the length of the feeding stroke, it .is necessary to loosen ring nut 43, to screw or unscrew cylindrical body 42 causing the variation of the length of chamber 19, and to then tighten said ring nut 43 in the new position.

By decreasing the length of chamber 19, a decrease in the distance between two consecutive buttonholes, is obtained while by increasing said length, an increase in the distance between two consecutive buttonholes is obtained.

When index 71, at the beginning of a feeding phase, is in the extreme right notch of the graduated scale; cylindrical body 42 delimiting the stroke of piston 18 is in its extreme right position and in this case the greatest displacement of the fabric is obtained and therefore the greatest distance between two consecutive buttonholes. There is the smallest displacement of the fabric and therefore the smallest distance between two consecutive buttonholes when index 71 is on the extreme opposite notch at the left of the graduated scale. In this case cylindrical body 42 is threaded completely into cylinder 10.

In FIG. 1, index 71 is in the intermediate notch of the graduated scale and the distance between two consecutive buttonholes has in this case an intermediate value between the greatest and smallest obtainable.

What is claimed is:

1. A sewing maching having a fabric feeding device comprising: a fabric gripping means and a drive means for driving said gripping means along a rectangular path, said drive means comprising a fluid actuated first cylinder having a first piston therein and a piston rod rigid with said first piston and rigidly attached to said gripping means, whereby reciprocations of said first piston are transmitted to said gripping means in correspondence to two of the parallel sides of said rectangular path, a second cylinder and piston therein, a multiway valve means for directing a pressurized fluid respectively into opposite ends of said second cylinder so as to drive the second piston alternately in opposite directions, said second piston being drivingly connected to the first mentioned cylinder so as to oscillatingly rotate said first mentioned cylinder and piston about their own axi's pursuant to reciprocations of said second piston to drive said gripping means along the other two parallel sides of said path.

2. The machine of claim 1, wherein the reciprocations of said first piston correspond to reciprocationsof said gripping means along the direction of fabric travel while the oscillatory rotations of said cylinder corre- 

1. A sewing maching having a fabric feeding device comprising: a fabric gripping means and a drive means for driving said gripping means along a rectangular path, said drive means comprising a fluid actuated first cylinder having a first piston therein and a piston rod rigid with said first piston and rigidly attached to said gripping means, whereby reciprocations of said first piston are transmitted to said gripping means in correspondence to two of the parallel sides of said rectangular path, a second cylinder and piston therein, a multi-way valve means for directing a pressurized fluid respectively into opposite ends of said second cylinder so as to drive the second piston alternately in opposite directions, said second piston being drivingly connected to the first mentioned cylinder so as to oscillatingly rotate said first mentioned cylinder and piston about their own axis pursuant to reciprocations of said second piston to drive said gripping means along the other two parallel sides of said path.
 2. The machine of claim 1, wherein the reciprocations of said first piston correspond to reciprocations of said gripping means along the direction of fabric travel while the oscillatory rotations of said cylinder correspond to opposed movements of said gripping means transversely to the direction of fabric travel.
 3. The machine of claim 1, wherein said valve means are Actuated by the first mentioned piston rod.
 4. The machine of claim 2, including a means to vary the length of stroke of said piston whereby the fabric feeding stroke of said gripping means is varied. 